Background of the Invention
Eliminating pathogenic microorganisms on various hard or soft surfaces typically found in residential homes and institutional environments, especially is where such organisms may stay active for relatively long periods of time, is critical to good cleaning and hygiene practices (S. F. Bloomfield and E. Scott, J. Appl. Microbiol. 83:1-9, 1997). Exemplary hard surfaces include counter-tops, bath tubs, sinks, drains, shower stalls and toilet bowls. Soft surfaces can be woven or nonwoven textiles such as shower curtain liners, clothing, carpeting and upholstery. There is a growing scientific recognition that bacterial organisms which actively populate these common surfaces may form organized communities called biofilms. Bacterial cells forming these biofilm communities assume a biological phenotype that is markedly different than their corresponding planktonic (non-surface attached) bacterial analogs (W. G. Characklis, xe2x80x9cMicrobial Biofouling Controlxe2x80x9d in Biofilms, Characklis and Marshall, eds., Wiley and Sons, 1990, J. W. Costerton, Ann. Rev. Microb. 49:7110-7145,1995). For example, current antimicrobial test methods for household cleaners employ a microbial inoculum of living planktonic bacteria.
One differentiating property between biofilm and planktonic bacteria is the greatly enhanced resistance to antimicrobial agents displayed by biofilm organisms. The significantly decreased susceptibility of biofilm cells to biocides has been documented in numerous recent studies. See for example: A. B. Ronner, et al., J. Food Prot. 56:750-758, 1993; J. W. Costerton, supra, 1995, P. Gilbert and M. R. W. Brown, Microbial Biofilms, Lappin-Scott and Costerton, Eds., University Press, 1995; S. Oie, et al., Microbios. 85:223-230, 1996; J. R. Das, et al., Changes In Biocide Susceptibility of Bacteria Following Attachment to Surfaces, poster presentation, American Society of Microbiology Conference on Microbial Biofilms, Snowbird, Utah, 1997; C. Ntasama-Essomba, et al., Veter. Res. 28:353-363, 1997, J. W. Costerton, Internat. J. Antimicrob. Agents 11:217-221, 1999.
This enhanced resistance to biocides for biofilm bacteria has been documented for antimicrobial agents traditionally used in biocidal cleaners for the residential home and institutional environments, such as quaternary ammonium compounds and chlorine-based oxidizing agents. Sanitizing and disinfecting cleaners using biocidal actives such as these may not meet required levels of microbial kill when used according to label instructions to treat biofilm-containing soils.
Effective cleaning of biofilm contaminated surfaces in residential homes and commercial institutions is essential for the maintenance of good environmental hygiene, where soils attached to surfaces are likely to contain biofilms (S. F. Bloomfield and E. Scott, supra, 1997). Thus, there is a significant need for biocidal compositions, which display high sanitizing and disinfecting power against biofilm-based microorganisms. Such compositions should be xe2x80x9cuser-friendlyxe2x80x9d, presenting minimal chemical hazard to the user. In addition, these cleaners should perform effectively under practical use conditions, such as short contact times and room temperature application. Ideally, such compositions would also be inexpensive, i.e., they would be largely aqueous in nature and utilize low cost reagents.
Specific biocidal compositions and/or methods for their use, which specifically address biocide resistant forms of bacteria, have been disclosed. For example, U.S. Pat. Nos. 5,444,094 and 5,908,854 disclose biocidal compositions and related methods of use involving combinations of select solvents with quaternary ammonium compounds for biocidal cleaners effective against mycobacteria, such as M. tuberculosis. U.S. Pat. No. 5,731,275 discloses aqueous cleaning and decontaminating compositions for use on biofilm coated surfaces. However, the cleaning and disinfecting conditions cited in U.S. Pat. No. 5,731,275 involve soaking the biofilm-contaminated surfaces in the inventive cleaning solutions for extended periods of time, typically 12-24 hours at room temperature. Such treatment conditions are unrealistic for most residential home and institutional cleaning applications where the user typically applies the biocidal product to the contaminated surface by spraying, followed by a short contact time (usually 10 minutes or less).
The present invention provides biocidal compositions that are highly effective at killing gram negative and gram positive biofilm-bound microorganisms and also address one or more of the above-mentioned technical formulation issues.
The present invention also provides a method for the effective sanitizing or disinfecting of biofilm-contaminated surfaces, comprising the steps of contacting or treating said surface with the described compositions of this invention.
In one embodiment, the present invention is a method of substantially reducing biofilm microorganisms on a surface comprising the step of applying a composition comprising (a) between 0.1% and 10% by weight of an anionic surfactant selected from the group consisting of alkyl sulfates, alkyl sulfonates, and aryl sulfonates with alkyl or aryl substituents; (b) between 0.1% and 10% by weight of an acid, preferably a weakly acidic organocarboxylic acid; and (c) between 0.5% and 10% by weight of a monohydric alcohol solvent. The pH of the composition is between pH 1 and pH 5, preferably between pH 2 and pH 4.
In a preferred version of the present invention, the anionic surfactant is present in an amount from about 0.25 to 8% by weight of the composition and is selected from the group consisting of sodium lauryl sulfate or sodium dodecylbenzene sulfonate.
In another preferred embodiment of the present invention, the acid is present in an amount between about 0.5% to about 5% by weight of the composition and is selected from the group consisting of citric acid, lactic acid, glycolic acid, gluconic acid, glucoheptonic acid, malic acid, glutaric acid, succinic acid, adipic acid, formic acid, oxalic acid, acetic acid, propanoic acid, benzoic acid, phthalic acid, malonic acid, sorbic acid, fumaric acid, tartaric acid, and mixtures thereof.
In another preferred embodiment of the present invention, the solvent is present in an amount of about 1.0% to about 5% by weight of the composition and is selected from the group consisting of aliphatic alcohols or a glycol ether.
The present invention is also a composition comprising (a) between 0.1% and 10% by weight of an anionic surfactant selected from the group consisting of alkyl sulfates, alkyl sulfonates, and aryl sulfonates with alkyl or aryl substituents, (b) between 0.1% and 10% by weight of an acid, and (c) between 0.5% and 10% of an aliphatic alcohol or glycol ether solvent, wherein the pH of the composition is between pH 1 and pH 5.
Other objects, advantages and features of the present invention are apparent to one of skill in the art after review of the specification and claims.